It Came From the Ala Wai: 6 Strange Creatures That Thrive in Waikīkī’s Sewage Filled Canal

What lurks in the murk of Honolulu’s most prominent drainage ditch? Lots of things, including a fish that can literally give you nightmares.

By David Thompson

Published: 2017.10.23 09:08 AM

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Photos: Elyse Butler Mallams

An old film clip in the archives of the Bishop Museum shows a group of children and adults, in early 20th-century swimwear, frolicking in the waters of the Ala Wai Canal. It probably dates to the 1920s, the same decade the two-mile-long canal was dug to drain Waikiki’s wetlands and create more buildable ground there.

People don’t swim in the Ala Wai anymore. Contact with its murky water—filled with bacteria, heavy metals, pesticides, and who knows what else—can be hazardous to your health. As the dedicated canoe paddlers who practice on the Ala Wai are well aware, even light splashes can cause rashes, boils and gastro-intestinal troubles.

As scary as the Ala Wai’s waters are, life thrives there. Sure, the canal is a massive drainage ditch for a swath of city stretching from Punchbowl to Diamond Head. But it’s also a tropical tidal estuary, where freshwater and seawater meet, producing a fruitful habitat for a wide variety of pollution-resistant fish, crustaceans and other creatures.

“It may be a toxic soup,” says Alan Friedlander, a National Geographic scientist specializing in coral reef ecology, “but it supports an awful lot of life.”

Friedlander walked the Ala Wai’s banks with us in an informal biological survey, helping us find a half dozen of those hardy, foul-water-loving life forms.

Olivia Nigro takes a water sample.

VIBRIO VULNIFICUS

The Ala Wai teems with bacteria, much of it originating in the intestinal tracts of the rats, dogs, mongoose and other animals that inhabit parts of Honolulu and its watershed that drain into the canal. These visiting microbes are dead-enders, washed into the Ala Wai but unable to reproduce there. There is, however, a type of bacteria that calls the Ala Wai home: Vibrio vulnificus.

This sinister-sounding pathogen is a natural part of estuaries such as the Ala Wai, one which can cause serious illness if it is ingested or enters an open wound. People with chronic disease are especially at risk. V. vulnificus gained notoriety in 2006, afer a man with chronic alcoholic liver disease died of a flesh-eating vibrio infection following a dunking in the Ala Wai. The immersion occurred the same week that a sewer line failed, forcing the city to dump 48 million gallons of raw sewage into the canal. But as V. vulnificus itself is not carried by human waste, the man’s vibrio infection may have been coincidental to the sewage, says Olivia Nigro, a microbrial oceanographer at the University of Hawaii, who was involved in testing the Ala Wai for vibrio following the spill.

Nigro returned to the Ala Wai in 2008 and 2009 to conduct a year-long study of V. vulnificus. She found that vibrio levels are significantly higher in the rainy months, from December through April. But even then levels varied greatly. Sudden rains sending fast-moving fresh water into the canal were followed by reduced levels of vibrio, while soaking mountain rains that produced long, slow influxes of fresh water into the canal brought the highest levels of vibrio—sometimes hundreds of times higher than they were after the sewage spill. “After a big rain, the Ala Wai looks very brown and dirty,” Nigro says. “But that’s not necessarily when the waters are most dangerous in terms of V. vulnificus.”